Regulated power unit



ugo 239 QO W R, KQCM 2,???5522 REGULATED POWER UNH l Filed Jan. 3l. 1936 Patented Aug. 23, 1938 PATENT OFFICEl REGULATED POWER UNIT Winfield R. Koch, Merchantville, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application January 31, 1936, Serial No, 61,777

10 Claims..

The present invention relates to regulated power units or potential supply units, for convertingr alternating current line power into direct current potentials and power, suitable for use with devices normally requiring constant voltage and necessitating the use of B" batteries as a source of such voltage. Such devices may include radio and audio frequency amplifiers for testing apparatus, for example, requiring a source of constant potential for the anode and bias supply circuits thereof.

The basic power supply unit may include an alternating current'step-up transformer, rectifier and filter means, together with an output or bleeder resistor to which the rectifier supplies rectified current at a, potential suitable for anode and other circuits. In regulated power supply units, however, means may be provided for maintaining substantially a constant potential at the terminals of the bleeder resistoror output terminals, through the intermediary of a regulating or control circuit including an electric discharge amplifier tube network.

Heretofore, it has been found desirable and substantially necessary to provide high resistance in the grid circuits of control tubes to obtain regulation and gain thereby precluding the use of more efficient and higher power tubes not adapted to so operate. Furthermore, while certain of the control tubes are heating, over-voltage may exist across the output impedance, and while undesirable, has not heretofore been overcome in a practical manner.

Accordingly, it is a primary object of the present invention to provide an improved regulated power supply unit having improved regulation with large current carrying capacity and which does not produce over-voltage when initially energized.

It is also an object of the present invention to provide an improved regulated power unit which supplies substantially constant direct current at the output potentials thereof with varying load and with varying alternating current supply potential with a higher degree of regulation, and in which the output potentials are maintained at safe subnormal values until the control tubes thereof have heated for proper operation.

It is also a further object of the present invention to provide an improved regulated power supply unit wherein higher capacity.regulating tubes may be utilized in connection with 10W resistance control circuits through the intermediary of a current amplifier.

The invention will,- however, be better under- (Cl. 17h-,312)

stood from the following description when considered in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing, the figure is a schematic circuit diagram of a regulated power supply unit embodying the invention, and in which the usual rectifier and filter circuit comprises an alternating current step-up transformer 5, provided with a. primary winding 6 connected through a power switch 1 with a plug 8 for the usual alternating current power outlet (not shown).

The transformer is further provided with a high voltage secondary 9 and filament supply secondaries I and Il, the former supplying a full wave rectifier tube i2, the anodes i3 of' which are connected with the high voltage secondary, Rectifled alternating current is taken from the center tap I4 on the secondary 9 and a filament connection I5 on the rectifier, through positive and negative output leads I6 and I1 respectively, the polarities of which are indicated.

The output circuit further includes a series filter inductance or choke coil I8 and shunt filter capacitors I9, the filter inductance being in the positive lead in this case.

The potential derived from the rectifier and filter is applied across an output or supply resistor comprising three lseries connected resistor sections 20, 2| and 22 through a plurality of parallel connected high capacity voltage reguiating tubes, 23, the parallel space current paths of the tubes being connected in Series between the positive output lead 24 of the filter and the high potential terminal 25 of the output resistor series. This arrangement is provided by connecting the anodes 26 ofl the voltage regulating tubes in parallel to the lead 24, while the cathodes 27 are connected in parallel across the filament supply Winding Ilfthe center tap 28 of which ls connected through a, supply lead 29 with the terminal 25.

The negative lead I1 of the rectifier output circuit is connected directly through a supply lead 30 with the negative terminal 3| of the series output resistor circuit. Suitable output terminals 32 and 33 are provided in connection with the output resistor and a negative output terminal 34 is provided in connection with the terminal 3l. Any other suitable taps may be provided on the series connected resistors for power supply purposes to utilization circuits (not shown).

The space path or anode impedance of the parallel connected voltage regulating tubes 23 provide, in effect, a variable resistance in series in flers are provided with heater type cathodes as indicated, they are initially inoperative to control the system. The voltage regulating tubes 23 may, therefore, receive the full biasing potential from the resistor 20 and the output current is thereby materially reduced below normal, whereby the output voltages across the terminals 32, 33 and 34 are reduced below a normal value thereby preventing over-voltage. Upon heating of the current amplier and control tubes to normal, the potential across the control or output resistor of the current amplifier operates to reduce the biasing potential on the voltage regulating tubes 23 to normal and a normal output potential is established across the output terminals 32, 33 and 34.

In case that the voltages between the terminals 32 and 33 and the terminal 34 tend to be reduced below normally desired and established values, by reason of load or by reason of a reduction in the supply potential derived from the rectier, the negative bias on the control grid 55 is increased, for the reason that the voltage between the tap 51 and the negative lead 30 regulates against the voltage provided by the regulating tube 52, The polarity of this voltage is indicated adjacent to the tube and it will be seen is in opposition to the drop in potential between the tap 51 and the negative lead 30 which is initially adjusted to some value below the constant voltage of the device 52, to permit a normal negative biasing potention to be placed on the grid 55. For example, if the tube 52 provides a drop in potential of 60 volts, the drop in potential selected across the potentiometer resistor 54, in opposition thereto, may be 54 volts, thereby resulting in an effective normal negative bias of 6 volts on the grid 55.

With the reduction in output potential from the power supply terminals 32, 33 and 34, under conditions above pointed out, the increase in negative bias on the grid 55 of the control tube causes a reduction of the anode current owing from the latter through the coupling resistor 48, thereby increasing the potential on the control grid 43 of the current amplifier in a'positive direction. This, in turn, causes the anode current of the 4ampliiier 4i to increase, resulting in a higher drop in potential through the output or control resistor 38 and greater opposition to the xed negative biasing potential derived from the resistor 20, whereby the grids of the,

voltage regulating tubes receive a lower negative biasing potential, thereby lowering their anode or plate impedance'and permitting increased current to flow to the output resistor, which, in turn, restores the potential to normal. An inl crease in the potential at the output terminals for any reason causes the system to operate in the opposite manner to restore the potential to normal. by increasing the plate impedance of the regulating tubes.

By utilizing low impedance voltage regulating tubes, which, in'turn, are made possible by the use of a direct current amplifier the output impedance of whichprovides a desired low resistance in the grid control circuit of the regulating tubes, a greater portion of the voltage supplied by the rectifier and lter is made available for use at the output terminals of the power supply unit.` Furthermore, by utilizing a current amplifier, the low resistance grid circuit is provided without additional voltage supply or change in direction of control. It should also be noted that the circuit shown and described, provides protection against over-voltage when the power supply unit is initially energized, or ii', for any against over-voltage because of faulty operation,

for-the reason that, if the control circuit fails by reason of the faulty operation of the control tubes, such as burning out of the heaters, the initial full negative bias is applied to the voltage regulating tubes 23 from vthe tap 40 on the resistor 20, whereby the output potential falls below normal.

. It is also preferable that the control tube or voltage amplifier 41 be of the high mu type, providing a wide range of voltage control through the output resistor 48 in connection with the gridof the current amplifier 4|. Furthermore, if any appreciable amount -oi ripple potential is present in the output circuit, the same may be applied to the grid of the control amplifier 41 through a coupling capacitor 58 connected between the grid circuit for the grid 55 and the high potential terminal 25 of the output resistor system, as indicated. Such a ripple is then suitably amplified without distortion through the current amplifier and is applied to the regulating tubes further to reduce the hum potentia as present in the output.

I claim as my invention:

1. A voltage regulating power supply unit cornprlsing a voltage supply circuit having positive and negative output leads, a voltage output resistor connected in shunt with said leads, a voltage regulating tube having its space path included serially in said last named connection and having a control grid whereby the impedance of said space path is varied, means including a grid control circuit connected with said output resistor adjacent to the positive end thereof to provide an initial negative biasing potential on said control grid, a direct current amplifier including an electric discharge device having a control grid, an anode connected with said positive supply lead, and a cathode connected with said voltage output resistor in common with said grid control circuit connection, a resistor in said last named connection providing with the resistance of said output resistora minimum total predetermined resistance in the grid circuit of the regulating tube', means providing an adjustable tap connection'adjacent to the negative end oi said output resistor, a voltage amplier tube having a control grid connected with said adjustable tap connection, and a cathode connected with the negative end of said output resistor, a voltage regulating tube in said last named connection providing substantially constant reference voltage f or said unit, and means for coupling said voltage amplifier to said control grid of the direct current amplier.

2. A regulated power unit comprising in combination, means for supplying electrical energy at substantially constant direct-current voltage including a positive and a negative supply lead, a load circuit connected with said supply leads and including a potentiometer resistor connected between said leads in shunt relation to said supply means, a regulating tube having an anode connected with the positive supply lead and a cathode connected with the load circuit, and having a control grid, a direct-current amplifier tube having an anode connectedY with the positive supply lead and having a cathode connected with a voltage tap point on said potentiometer resistor, said rst named control grid being connected with said last named cathode, a cathode resistor connected between said last named cathode and said voltage tap point, said resistor having a resistance less than a predetermined minimum, a control tube coupled to said direct-current amplifier, means providing substantially constant biasing potential for said control tube, and means for deriving a controlling potential `from said potentiometer resistor adjacent to the negative end thereof for said control tube in opposition to said substantially constant potential.

3. A regulated power supply unit comprising, in combination, a direct current supply circuit, a power output resistor having positive and negative terminals, at least one electric discharge regulating tube having its anode-cathode impedance in circuit between the positive side of said supply circuit and the positive terminal of said output resistor, and said tube having a control grid adapted to receive a controlling potential whereby the internal impedance of said tube is controlled, a grid circuit for said control grid including a series potential drop producing resistor and a tap connection on said output resistor adjacent to the positive terminal thereof, whereby an initial negative bias potential as applied to said control grid from said output resistor, said bias potential being such that the internal impedance of at least one regulating tube is relatively high with respect to the normal internal impedance of said tube, a current amplifier tube having an anode connected with the positive side of said supply circuit, a cathode connected with the grid end of said last named potential drop producing resistor, and a control grid, a voltage amplifier tube having an anode connected in parallel with said last named grid and having a common connection therewith to the positive side of said supply circuit, a coupling resistor in said connection, said voltage amplifier having a control grid and a cathode, said cathode being connected -with the negative side of said supply circuit, a voltage regulator tube in said connection providing a constant reference voltage for said unit, and a tap connection for said last named grid on said output resistor adjacent to the negative terminal thereof to provide a positive potential on said last named grid substantially less than the potential provided by said regulating tube.

4. In a regulated power supply unit comprising a direct current supply circuit, at least one regulating tube and a power output resistor in series across said circuit, the combination of a grid circuit for said regulating tube comprising a series resistor and a portion of the output resistor adjacent to the positive terminal thereof, the totalresistance of which circuit is less than a predetermined minimum, a current amplifier tube having a cathode connected with said series resistor at a point to place said resistor jointly in the cathode circuit of said last named tube and the grid circuit of said first named tube, said current amplifier having an anode connected with the positive side of said supply circuit, a voltage amplifier tube having an anode and said current amplifier having a grid, a coupling resistor common to said anode and grid providing a connection therefor with the positive side of said supply circuit, said voltage amplifier further having a control grid and a cathode, and means providing a source of substantially constant voltage and a portion of said output resistor adjacent to the negative terminal thereof between said last named control gridA and cathode, said connection with the output resistor being variable.

5. In a regulated power supply unit comprising a direct current supply circuit, at least one regulating tube and a power output resistor in series across said circuit, the combination of a grid circuit for said regulating tube comprising a series resistor and a portion of the output resistor adjacent to the positive terminal thereof, the total resistance of which circuit is less than a predetermined minimum, and a current amplifier tube having a cathode connected with said series resistor at a point to place said resistor jointly in the cathode circuit of said last named tube and the grid circuit of said first named tube.

6. In a regulated power supply unit comprising a direct current supply circuit, at least one regulating tube and a power output resistor in series across said circuit, the combination of a grid circuit for said regulating tube comprising a, series resistor and a portion of the output resistor adjacent to the positive terminal thereof, the total resistance of which circuit is less than a predetermined minimum, a current amplifier tube having a cathode connected with said series resistor at a point to place said resistor jointly in the cathode circuit of said last named tube and the grid circuit of said first nnamed tube, said current amplifier having an anode connected with the positive side of said supply circuit, a, voltage amplifier tube having an anode and said current amplifier having a grid, a coupling resistor common to said anode and grid providing a connection therefor with the positive side of said supply circuit, said voltage amplifier further having a control grid and a cathode, and means providing a source of substantially constant voltage and a portion of said output resistor adjacent to the negative terminal thereof between said last named control grid and cathode, said connection with the output resistor being variable, said current amplifier and said voltage amplifier being of the indirectly heated cathodev type and said regulating tube being of the filamentary type, whereby when said power unit is energized, the output current applied to said output resistor is reduced initially and until said current and voltage amplifiers are rendered operative.

'l'. In a regulated power supply unit, the combination of a direct current supply circuit, a power output resistor having a negative terminal connected with the negative side of said supply circuit and having a. positive terminal connected with the positive side of said supply circuit, at least one regulating tube connected between said positive terminal and the positive side of said supply circuit whereby the anode-cathode impedance thereof is included in circuit with said output resistor, said tube having a control grid whereby said impedance is controlled by the application of a biasingpotential thereto with respect to cathode, a gridcircuit for said regulating tube connected with said output rei heated cathode and an anode directly connected with the positive side of said supply circuit and having a cathode connection in common with said iirst named grid circuit to said tap on said output resistor, and a resistor of less than a predetermined minimum resistance in said last named common connection.

8. In a regulated potential supply system, the

combination with a direct current supply circuitl and at ieast'one regulating tube having a cathode, an anode connected with the positive side of the supply circuit and a control grid, of means for deriving potentials therefrom comprising a voltage output resistor having a positive terminal connected with the cathode, and having a negative terminal, a direct current amplifier tube having an anode connected with the positive side of the supply circuit, and having a cathode connected with the control grid of said regulating tube, a common resistor for said last named cathode and control grid of a predetermined maximum resistance, connected with said output resistor adjacent to the positive terminal thereof to establish a predetermined initial biasing potential on said grid, and means connected with the negative end of said output resistor to receive a controlling potential therefrom for said direct current amplifier tube.

9. In a regulated potential supply system, the combination with a direct current supply circuit and at least one regulating tube having a cathode, an anode connected with the positive side of the supply circuit and a control grid, of means for deriving potentials therefrom comprising a voltage output resistor having a positive terminal connected with the cathode, and having a negative terminal, a direct current amplifier tube having an anode connected with the positive side of the supply circuit, and having a cathode connected with the control grid of said regulating tube, a common potential drop producing impedance device for said last named cathode and control grid connected with said output resistor adjacent to the positive terminal thereof whereby a positive bias potential for the last named control grid is provided by said impedance device and an opposing negative biasing potential is provided by said output resistor through said connection, and means for adjusting said connection to provide a predetermined relation between said biasing potentials` l0. In a regulated potential supply system, the combination with a direct current supply circuit and at least one regulating tube having a cathode, an anode connected with the positive side of the supply circuit and a control grid, of means for deriving potentials therefrom comprising a voltage output resistor having a positive terminal connected with the cathode, and having a negative terminal, a direct current amplifier tube having an anode connected with the positive side of the supply circuit, and having a cathode connected with the control grid of said regulating tube, a common potential drop producing impedance device for said last named cathode and control grid connected with said output resistor adjacent to the positiveterminal thereof whereby a positive bias potential for the last nained control grid is provided by said impedance device and an opposing negative biasing potential is provided by said output resistor through said connection, means for adjusting said connection to provide a predetermined relation between said biasing potentials, a control tube, a regulating tube, a circuit comprising a resistor, the anode-cathode impedance of said control tube and space path of said regulating tube connected serially in the order named between the positive and negative sides of the supply circuit, a control grid for the direct current amplifler connected with said last named circuit between the resistor and the control tube, and a control grid for the control tube connected with the voltageV output resistor adjacent to the negative terminal thereof.

WINFIELD R. KOCH. 

